Deepen your breathing. Presently, take nine more. A newly discovered cellular mechanism that encourages photosynthesis in marine phytoplankton allowed for the amount of oxygen in each of those ten breaths, according to new research.
This previously unknown process accounts for between 7% and 25% of all oxygen produced and carbon fixed in the ocean, according to a group of researchers at the Scripps Institution of Oceanography at the University of California, San Diego. It has been dubbed “groundbreaking” by them. Researchers estimated that this mechanism could generate up to 12% of the world’s oxygen if they also took into account land-based photosynthesis.
Due to their ability to photosynthesize, scientists have long recognized the significance of phytoplankton—microscopic organisms that drift in aquatic environments. The base of the aquatic food web is made up of these tiny oceanic algae, which are estimated to produce approximately half of the oxygen in the world.
VHA, a proton pumping enzyme, plays a role in phytoplankton’s global oxygen production and carbon fixation, according to a new study in Current Biology.
“We think of proteins like Lego blocks. The proteins always accomplish the same thing, but depending on the other proteins with which they are partnered, they can perform a completely different role.”
Scripps physiologist Martín Tresguerres, one of his co-advisors,
Lead author Daniel Yee, who was a Ph.D. student at Scripps Oceanography and now works as a joint postdoctoral researcher at the European Molecular Biology Laboratory and the University of Grenoble Alpes in France, said, “This study represents a breakthrough in our understanding of marine phytoplankton.”
“These small cells in the ocean have evolved over millions of years to carry out minute chemical reactions, especially to produce this mechanism that improves photosynthesis and has shaped the course of life on this planet.”
Yee deciphered the intricate inner workings of a particular group of phytoplankton known as diatoms, which are single-celled algae that are renowned for their ornamental cell walls made of silica. Yee worked closely with Scripps physiologist Martn Tresguerres, one of his co-advisors, and other collaborators at Scripps and the Lawrence Livermore National Laboratory.
Understanding the ‘proton siphon’ compound
Past examinations in the Tresguerres Lab have attempted to recognize how VHA is involved by different living beings in processes basic to life in the seas. This enzyme’s primary function is to alter the pH level of the surrounding environment. It can be found in nearly all forms of life, from humans to single-celled algae.
Tresguerres, a co-author of the study, explained, “We imagine proteins as Lego blocks.” The proteins always carry out the same action, but the outcomes can vary greatly depending on the other proteins they are paired with.
The enzyme helps the kidneys regulate the functions of the blood and urine in humans. Goliath mollusks utilize the compound to disintegrate coral reefs, where they emit a corrosive that drills holes in the reef to take cover.
Corals utilize the chemical to advance photosynthesis through their harmonious green growth, while remote ocean worms known as Osedax use it to break down the bones of warm-blooded marine creatures, like whales, so they can consume them. Additionally, the enzyme is a component of a mechanism that regulates blood chemistry in shark and ray gills. What’s more, in fish eyes, the proton siphon conveys oxygen that improves vision.
Yee was curious about the utilization of the VHA enzyme in phytoplankton after reviewing this previous study. He set out to answer this question by combining genetic tools developed in the lab of the late Scripps scientist Mark Hildebrand, a leading diatom expert and one of Yee’s co-advisors, with high-tech microscopy methods in the Tresguerres Lab.
He was able to precisely locate the proton pump around chloroplasts, also known as “organelles” or specialized structures within diatom cells, by using these tools to apply a fluorescent green tag to them. Diatoms’ chloroplasts have a thicker membrane than those of other algae, enclosing the area where light energy and carbon dioxide are transformed into organic compounds and released as oxygen.
According to Yee, “We were able to generate these images that are showing the protein of interest and where it is inside of a cell that has many membranes.” In combination with definite trials to evaluate photosynthesis, we observed that this protein is really advancing photosynthesis by conveying more carbon dioxide, which is what the chloroplast uses to deliver more mind-boggling carbon particles, similar to sugars, while likewise creating more oxygen as a result.”
Connection to evolution
After determining the underlying mechanism, the team was able to link it to a number of aspects of evolution. Around 250 million years ago, a symbiotic event that culminated in the fusion of the two organisms into one, known as symbiogenesis, gave rise to diatoms.
The authors emphasize that phagocytosis, or the act of eating another cell, is common in nature. The proton pump is used by phagocytosis to digest the food-producing cell. Diatoms, on the other hand, experienced a unique circumstance in which the consumed cell was not fully digested.
According to Tresguerres, “Instead of one cell digesting the other, the acidification driven by the predator’s proton pump ended up promoting photosynthesis by the ingested prey.” Diatoms are the result of the fusion of these two distinct organisms over the course of evolution.”
Not all green growth has this system, so the creators feel that this proton siphon has given diatoms a benefit in photosynthesis. They likewise note that when diatoms began a long time ago, there was a major expansion in oxygen in the environment, and the newfound component in green growth could have had an impact on that.
It is believed that the majority of fossil fuels extracted from the ground came from the transformation of biomass, including diatoms, that sank to the ocean floor over millions of years, creating oil reserves.
Biotechnological strategies to enhance photosynthesis, carbon sequestration, and biodiesel production can learn from the findings of the study, the researchers hope. In addition, they anticipate that it will enhance our comprehension of ecological interactions, global biogeochemical cycles, and the effects of environmental changes like climate change.
According to Tresguerres, “This is one of the most exciting studies in the field of symbiosis in the past decades, and it will have a significant impact on future research worldwide.”
More information: Daniel P. Yee et al, The V-type ATPase enhances photosynthesis in marine phytoplankton and further links phagocytosis to symbiogenesis, Current Biology (2023). DOI: 10.1016/j.cub.2023.05.020. www.cell.com/current-biology/f … 0960-9822(23)00615-2
